In recent years, in response to societal demands, lower environmental impact fuel injection systems (referred to as “F.I. system” below) are becoming mainstream as the fuel supply systems for the engines in saddle type vehicles. Usually, in an F.I system, a fuel pump pumps the fuel from inside a fuel tank to the engine injector.
Within an F.I. system, if the vehicle is driven and the engine is stopped when the engine has reached a high temperature, vaporized fuel (referred to below as vapor) may be generated in the fuel pump or in a pipe connecting the fuel pump and the fuel tank. The vapor may be caught in a filter used for removing the foreign particulates contained in the fuel, or may build up in the pipe and therefore inhibit the flow of fuel. Therefore, in the case where the engine is stopped after reaching a high-temperature, and the engine is restarted after a considerable amount of time has passed since the engine has stopped (referred to below as the “high-temperature restart time”), the vapor becomes the primary cause of degradation in the startup performance.
For instance, in the fuel supply system described in Japanese Laid-open Patent Publication Number 2011-220160, the fuel pump is placed below the fuel tank. The fuel pump pumps the fuel from inside the fuel tank to the injector. Additionally, a cylindrical filter is placed above the fuel pump. The top end of the filter is formed flat. In other words, the top end of the cylindrical filter is flat and orthogonal to the progression direction of the vapor generated inside the fuel pump. The fuel supply system described in Japanese Laid-open Patent Publication Number 2011-220160 relates to the ability of the vapor to be discharged from the inside of the filter to the outside.